The invention relates to a method of reducing or eliminating the pain from injections or minor surgical procedures by the local application of pressure about the injection or surgical site to block afferent pain fiber transmission. The invention further relates to devices that can be used to apply local pressure to an injection or surgical site to reduce or eliminate the pain associated therewith.
The pain elicited by administering minor injections, such as those with childhood immunizations, is a significant cause of stress in the medical office. It causes fear and anxiety in patients both young and old. It can create difficulties in developing patient rapport and confidence, and can even impair the physician's ability to perform an examination because of a patient's overriding preoccupation with the forthcoming shot or procedure. Any procedure and/or device that diminishes the pain associated with simple injections or minor surgical procedures would be of great help.
Such a procedure and/or device could be especially useful, as another example, to those with diabetes. Diabetes is a common disorder of the endocrine system affecting millions of individuals worldwide. In diabetes, the body loses its ability to manufacture insulin, a hormone produced normally in the islets cells of the pancreas. Insulin has many functions, but its primary function is to promote glucose uptake from the blood into the cells of the body where it can be metabolized to provide energy for those cells. In diabetes, the lack of insulin causes blood sugar to rise to dangerously high levels, causing dehydration and possible brain injury. At the same time, cells starved for glucose turn to fat metabolism for energy production, causing ketonemia and life threatening acidosis.
This severe disruption of the body's physiology and many of the later sequellae of diabetes can be avoided by giving insulin to diabetic patients. However, because insulin is a protein, the only currently available forms of the hormone must be given via injection. The sites chosen are usually the thigh and the abdomen, and diabetic patients often must take multiple injections of insulin daily. Newer treatment protocols advocate even tighter control involving six or more injections daily.
The pain elicited by chronic insulin injections is a constant source of anxiety and stress to the diabetic patient. Even when resigned to a lifetime of insulin injections, the pain associated with daily insulin shots is never appreciated. In fact, in some cases such pain can keep the diabetic patient from following a more aggressive insulin protocol just so he/she can avoid the increased number of injections. It will be appreciated that any device and/or procedure that diminishes the pain associated with daily insulin injections would be of great help.
Current studies have supported the gate control theory of pain awareness and transmission. Briefly stated, pain is elicited when noxious stimuli trigger nociceptive nerve endings in the skin. Pain impulses are then transmitted by small diameter peripheral afferent fibers through the spinal cord to the brain. Gate theory states that there is a gating mechanism in the dorsal horn of the spinal cord that acts to facilitate or inhibit transmission of pain signals to the brain. Stimulation of the small diameter nociceptive (pain) fibers opens the gate. The gate can be closed by simultaneous stimulation of large diameter afferent sensory nerve fibers, such as those that respond to mechanical stimuli such as touch and vibration.
Although gate control theory probably oversimplifies the true complexity of the body's regulation of pain, it has proved to be a useful guide to understanding and predicting pain and its control. Practical application of gate control theory has led to the development and widespread use of TENS units. TENS, transcutaneous electrical nerve stimulation, stimulates large diameter afferent sensory fibers with repetitive electrical impulses to use gate control to block pain signals from small diameter afferent pain nerve fibers. In many individuals with chronic pain TENS units employing the gate control theory of pain management provide significant and predictable relief from their pain.
Anecdotal experience by physicians has shown that the local application of pressure can reduce the pain from simple injections. A recent study was performed that documented and quantified this ability of simple applied finger pressure to reduce needle pain. These findings, reported in the Journal of Pain and Symptom Management, Vol. 12, No. 1, July 1996, pp. 52-58, support gate control theory and provide evidence that mechanical pressure can directly affect a person's sensation of pain.